The Lao Baiwen script was used for writing the Bai languages spoken in China. There are three varieties of Bai, Jianchuan (Central), Dali (Southern), and Bijiang (Northern). It is not agreed upon whether these should be classified as dialects or as distinct languages. The ethnologue separates them into three distinct languages. A Bai script has been in use since around the 8th century, but this was never standardized. A Latin-based orthography has now largely replaced the traditional Lao Baiwen script. This is based on the Central Jianchuan Bai language, but also accommodates features of the other two Bai languages.
This script is not currently recognized by ISO 15924, but is included in ScriptSource for research purposes. If you have any information on this script, please add the information to the site. Your contributions can be a great help in refining and expanding the ISO 15924 standard.